loader: fix elf lookup_symbol type filtering

The existing logic doesn't seem to make much sense, as we won't filter
on the type if st_shndx != SHN_UNDEF.  In practice, this breaks booting
12.3 kernels on newer loaders, as they do have a `kernphys` symbol of
the wrong type (NOTYPE, rather than OBJECT) -- we end up deriving the
wrong value for copy_staging.

It's unclear if this version makes any more sense, but it seems to match
what rtld's matched_symbol() does.  Loader doesn't need to care about
STT_FUNC w/ UND shndx, because we won't encounter those; in kmods,
undefined (kernel) functions are NOTYPE.

Approved by:	so
Security:	FreeBSD-EN-22:27.loader
Reported by:	Christian McDonald <cmcdonald netgate com>
Reviewed by:	imp, kib, tsoome

(cherry picked from commit 0701dbda94)
(cherry picked from commit 2b31059ea7)

stand/common/load_elf.c

@@ -1259,9 +1259,8 @@ __elfN(lookup_symbol)(elf_file_t ef, const char* name, Elf_Sym *symp,
 		strp = strdupout((vm_offset_t)(ef->strtab + sym.st_name));
 		if (strcmp(name, strp) == 0) {
 			free(strp);
-			if (sym.st_shndx != SHN_UNDEF ||
-			    (sym.st_value != 0 &&
-			    ELF_ST_TYPE(sym.st_info) == type)) {
+			if (sym.st_shndx != SHN_UNDEF && sym.st_value != 0 &&
+			    ELF_ST_TYPE(sym.st_info) == type) {
 				*symp = sym;
 				return 0;
 			}